This application claims the priority of German application 197 08 901.1, filed Mar. 5, 1997 in Germany, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a shaft brake disk for disk brake systems of rail vehicles, with a friction ring of light metal at its inner circumference connected by bolts with a hub flange projecting from the hub.
Brake disks for axles/disks of rail vehicles are either made in one piece (monobloc disks) or of individual parts, to improve their performance. Both traditional iron disks and light-metal friction rings, made of magnesium/aluminum for example, are connected with a steel hub such that the friction ring can expand preferably radially for example as it heats and at the same time transmits the braking torque. The hub itself is pressed or shrunk onto the axle or shaft (with heating) in the normal manner.
To reduce the weight of brake disks of the type in question, friction rings made of ceramic-reinforced aluminum have recently been developed and have achieved a weight reduction of approximately 40%.
A goal of the invention is to achieve a further weight reduction with shaft disk brakes of this type without impairing the quality of braking torque transmission. This goal is achieved according to preferred embodiments of the invention by providing a heat insulating layer between the hub flange and the friction ring.
By using hubs made of aluminum, a further weight reduction of another 10% is achievable, which is an important factor in brake disks operating at high speed. The problem of the relatively low strength of the light metal, of the low elasticity modulus, and the very high thermal expansion coefficients is solved according to the invention by providing a heat insulating layer between the inner circumference of the shaft brake disk and the supporting hub flange, said layer cutting heat transmission between the light-metal friction ring and the light-metal hub to the point that the critical temperature range of approximately 120-140.degree. C. is not exceeded. Thus, transmission of braking torque between the hub and axle or shaft is not impaired. The heat insulating layer, in the vicinity of the bolts that serve for the bolted connection between the friction ring projections and the hub flange, comprises insulating elements traversed by the bolts, in the form of insulating disks or insulating plates. The insulating layer can also comprise an insulating ring that surrounds the bolts and has through bores for the bolts.
Advantageously, a clamping ring on the opposite side of the hub flange and made of light metal, in contrast to traditional designs can be made of aluminum, with a heat insulating layer being provided in this area also, between the clamping ring and the friction ring projections.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.